August 18, 2007

Climate models of the 1980s

We will not be able to check whether today's climate models are 'right' until after the climate has occurred. But what we can do right now is check how old climate models did, say the climate models of the 1980s. These models are rather primitive by today's standards.

These figures show what climate models of the 1980s predicted as of 1990, and what actually occured in the subsequent years.

*Atmospheric carbon dioxide concentration (day by day oscillates, dark blue is running average, dashed blue and other colors are predictions) grew almost exactly as predicted in 1990.

*The Earth's temperature increased more than predicted. Red and blue points are two widely used global global data sets (one U.S., one U. K.); red and blue bold lines smooth out annual variation. The grey zone is what the climate models predicted, given specific emissions scenarios (colored dotted lines).

*Sea level (red from tide gauges and blue from satellite altimetry) has increased more than the models predicted (grey and dotted).

Conclusion: the models running in the 1980s were overly cautious in predicting changes in temperature and sea level.


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